Process for the synthesis of tertiary phosphine oxides and sulphides, and new tertiary phosphine oxides and sulphides

ABSTRACT

The invention relates to processes for the synthesis of tertiary phosphine oxides and sulphides. The process according to the invention consists, in a first step, of reacting a secondary phosphine oxide or sulfide with an optionally activated alkali metal amide, and, in a second step, of reacting the mixture obtained in the first step with an organic halide containing at least one halogenophenyl radical or one halogenomethyl group. Tertiary phosphine oxides and sulphides are complexing agents of high stability.

Tertiary phosphine oxides and sulfides are amongst the most stable ofthe organic phosphorus derivatives. This stability, together with thecomplexing properties of these products, make them extremely attractive.Thus, the synthesis of these compounds has formed the subject of diverseand thorough investigations.

To illustrate the diversity of the proposed methods of synthesis, theremay be mentioned French Pat. No. 2,159,716 assigned to Societe Nationaledes Poudres et Explosifs, which is based on the reaction of phosphorusoxychloride or PSCl₃ with a Grignard reagent, French Pat. No. 1,399,743,which recommends the reaction of an oxygen/PCl₃ mixture with the samemagnesium compounds, U.S. Pat. No. 3,258,492, which uses a phosphonylchloride, and also German Pat. No. 1,912,708, French Pat. No. 2,316,244,U.S. Pat. No. 3,997,611 and U.S. Pat. No. 4,020,110, which respectivelyrelate to the thermal decomposition of the addition product of adialkylphosphine oxide and an α-olefine, of a quaternary phosphoniumhalide, of a hydroxylated quaternary phosphonium halide and of ahydroxymethylated tertiary phosphine. Another method, involving thereaction of phosphorus with an alkyl iodide in the presence of iodine,as illustrated in French Pat. No. 2,352,824, may also be mentioned.

Another method of synthesis consists of condensing a halogeno-magnesiumsalt of a secondary phosphine oxide with an organic halogen derivativein accordance with the equation: ##STR1## A process of this type hasbeen described and studied, in particular by Downie and Morrs, Journalof the Chemical Society (1965), page 5,771. The disadvantage of thisprocess lies in particular in the slowness of the reaction and in theprecautions which any use of magnesium compounds necessarily involves,namely a rigorously anhydrous medium and increased safety measures dueto the use of ether in bulk.

Some authors, such as Petrov et al., Zh. Obshch. Khim 30, 1,964 (1960),have therefore recommended, instead, the use of an alkali metalphosphinite according to the equation: ##STR2## in which M=Li, Na or K.

However, these same authors do not avoid the abovementioneddisadvantages because they still use a magnesium compound to prepare thesaid alkali metal phosphinite. In order to dispense completely with theuse of a magnesium compound in this step, other authors have proposedsolutions starting from phosphine oxides or sulphides:

(1) Emoto et al., Bulletin of the Chemical Society of Japan, Volume 47(10), pages 2,449-2,452 (1974), propose the application of the reaction:

    Ph.sub.2 PXH+n-BuLi→Ph.sub.2 PXLi+C.sub.4 H.sub.10, in which X=O or S.

(2) Osipenko et al., in Zhurnal Obshchei Khimii, Volume 47, No. 11,pages 2,620-2,621 (1977), start from a secondary phosphine oxideaccording to the equation:

    Bu.sub.2 POH+2K→Bu.sub.2 POK+KOH, in THF.

(3) Horner et al., in Chemische Berichte, 94 (1961), pages 1,317-1,322,propose the reaction (which can be explosive) of an alkali metal hydridewith a tertiary phosphine oxide:

    R.sub.3 PO+MH→R.sub.2 POM+RM.

These solutions can be criticised in that, in (1), n-BuLi is expensiveand dangerous, in (2), potassium metal is used, which is dangerous andrelatively more expensive than sodium and lithium, and in (3), it isnecessary to use a high temperature (160° to 300° C. depending on thenature of M) and to start from a tertiary phosphine oxide, that is tosay from a compound of the same type as that which it is ultimatelyintended to obtain.

Furthermore, although the prior art as a whole offers fairlysatisfactory solutions for the synthesis of the alkali metalphosphinites or thiophosphinites, there remains the fact that reaction(A) according to Petrov et al. (op.cit.) has only proved entirelysatisfactory hitherto in exceptionally favourable cases.

Thus, if an alkali metal diphenylphosphinite is used, there isexceptional stabilisation of the reaction intermediate, and reaction (A)is highly favoured. It is not astounding under these conditions thatGerman Patent Specification No. 1,948,987, which uses a very reactivepotassium phosphinite, makes it possible to succeed in grafting groupsR₃, even reactive groups R₃, of the macromolecular type; likewise, it isnot surprising that Emoto et al. (op.cit.) have done the same in thecase where R₃ =CH₃, the process being made even easier here by the useof iodide in preference to a bromide or a chloride, or that GermanPatent Specification No. 1,167,831, which is also restricted todiphenylphosphinous acid, permits a rapid reaction in the presence of analkali metal alcoholate.

Using a comparable method, Osipenko et al. (op.cit.) only obtain goodresults when using a halide of the type R₃ X in which the group R₃ isstrongly activated (a methoxy group on the α-carbon), and this is alsoat the expense of a very long reaction time. If, on the other hand, anorganic halide in which R₃ is not activated is used, it is found, as byHorner et al. (op.cit.), that very long times and very high temperaturesare required in order to obtain a good yield.

Finally, despite the numerous investigations carried out by researchworkers with very different outlooks, it must be stated that there is noknown process which makes it possible easily to manufacture an alkalimetal dialkylphosphinite or dialkylthiophosphinite and to facilitate thereaction of the latter with a non-activated organic halide.

It is this object, together with other advantages, in particular inrespect of the costs and the safety, which the invention proposes toachieve.

This process according to the invention is a process for the synthesisof tertiary phosphine oxides or sulfides of the formula R₁ R₂ R₃ PZ, inwhich Z=S or O, which consists, in a first step, of obtaining an alkalimetal dihydrocarbyl(thio)phosphinite of the formula R₁ R₂ PZM from thecorresponding dihydrocarbylphosphine oxide or sulphide R₁ R₂ PZH, andthen, in a second step, in reacting the said alkali metaldihydrocarbyl(thio)phosphinite with an organic halide of the formula R₃X, characterised in that the first step is carried out by reacting analkali metal amide of the formula MNH₂ with the saidhydrocarbylphosphine oxide or sulfide, the second step being carried outin the presence of the untreated part of the said alkali metal amide.

According to a variant of the process according to the invention, thealkali metal amide is activated in the form of molecular associationsbased on an alkali metal alcoholate, based on a salt chosen from thegroup comprising the thiocyanates, the cyanates, the nitrites and thecyanides of sodium, lithium or potassium, or based on an organo-alkalimetal compound.

Lithium amide, sodium amide or potassium amide is preferably used as thealkali metal amide, with a particular preference for sodium amide, whichis the least expensive. As the dihydrocarbylphosphine oxide or sulfideof the formula ##STR3## in which Z=S or O, it is possible, inparticular, to use those in which R₁ and R₂ are identical or differentand are a linear or branched C₁ to C₁₈, preferably C₁ to C₁₂, alkylgroup, a C₇ to C₁₀ arylalkyl group, a phenyl group or a C₇ to C₁₂ arylgroup, or a C₇ to C₁₀ alkaryl group, or R₁ and R₂, taken together, forma C₄ to C₉ polymethylene chain or a C₄ to C₉ hydrocarbon chaincontaining at least one ethylenic unsaturation.

As the organic halide of the formula R₃ X, it is possible, inparticular, to use those in which X=Cl, Br or I and preferably those inwhich X=Cl or Br, and those in which R₃ is an aromatic group optionallysubstituted by other X atoms and containing from 6 to 14 carbon atoms,or a group CH₂ R₄, in which R₄ is a linear or branched primary alkylgroup containing from 1 to 18 carbon atoms, a primary aralkyl groupcontaining 7 to 14 carbon atoms, an alkaryl group containing from 7 to14 carbon atoms or a primary alkylene group containing from 3 to 18carbon atoms, one unsaturation not being directly bonded to X, or agroup --CH₂ X, in which X has one of the above meanings, or a group--CH₂ R₅ X, in which X has one of the above meanings and in which R₅ isa hydrocarbon chain containing from 1 to 18 carbon atoms, or a group##STR4## in which X has one of the above meanings, or also a crosslinkedmacromolecular group or a macromolecular group with a molecular weightof between 500 and 1,000,000, containing at least one other group Xcarried by an aromatic nucleus or a primary carbon of an aliphaticchain.

More generally, the invention is applicable to any condensation of analkali metal (thio)phosphinite with an organic halogen derivative ororganic polyhalogen derivative containing at least one halogen atom inthe form of a halogenoaryl group or halogenomethyl group.

If the organic halogen derivative is a macromolecule, it can be chosen,in particular, from the group comprising chloromethylated polystyrene,poly-(p-bromostyrene), poly-(p-chlorostyrene), bromopolybutadiene, andcopolymers containing the latter polymers, such as a Merrifield resin,that is to say an optionally partially crosslinked, random copolymer ofstyrene and a p-halogenomethylstyrene, which is moreover described indetail in French Application No. 79/31,917 of Dec. 28, 1979, filed inthe name of the Applicant Company. Another example is the polymer,carrying bromopolymethylene groups and derived from polystyrene, whichis obtained by Tundo and described by this author in ChemicalCommunications 1978, 315.

The molar proportion of alkali metal amide to be used, relative to thedihydrocarbylphosphine oxide (or sulfide) is equal to at least thestoichiometric proportion and is preferably between 1.1 and 6 times thisstoichiometric proportion, the maximum apparently being 20 times. Inother words, according to the invention, between 1 and 20 mols andpreferably from 1.1 to 6 mols of alkali metal amide are used per mol ofdihydrocarbylphosphine oxide (sulfide).

The proportion of dihydrocarbylphosphine oxide (or sulfide) to be used,relative to the organic halogen derivative, is generally consistent withthe stoichiometry, that is to say one mol of oxide (or sulfide) per molof halogen. However, depending on whether or not it is desired to effectcomplete substitution of the halogen atoms in the organic halogenderivative, it is possible to use between 0.1 and 20, preferably between0.5 and 3, mols of oxide (or sulfide) per mol of halogen, a largerexcess of oxide (or sulfide) corresponding to a particularly high degreeof substitution, especially in the case of macromolecular halogenderivatives.

Although the presence of a solvent does not seem to be essential duringeach step of the process according to the invention, it is neverthelesswholly desirable. It is possible, in particular, to use a non-polar orpolar, aprotic inert solvent, or a mixture of such solvents, as thesolvent medium. A suitable solvent is tetrahydrofuran, but it ispossible to use less polar solvents such as aliphatic or aromatichydrocarbons, in particular toluene, xylenes and hexane. Solvents whichare sensitive in a strongly basic medium, and halogen-containingsolvents, should preferably be avoided.

The temperature of the reaction medium during each of the steps isadvantageously ambient temperature, in strong contrast with the majorityof the earlier processes. Good results during the first step are onlyobtained by adopting a temperature between -20° and +70° C., preferablybetween 15° and 50° C. The second step is advantageously carried out atbetween -20° and +100° C., preferably at between 10° and 60° C. Underthese conditions, the first step can be completed within a period oftime of between a few minutes and 3 hours and the second step can becompleted within a few minutes to about ten hours for the mostintractable cases in which the steric hindrances is very considerablearound the halogen atom or around the (thio)phosphinite group.

In general, it is advantageous to carry out the reaction using suitablydried reactants and under an inert atmosphere, although the alkali metalamide can act as an effective and inexpensive desiccant without theprocess suffering as a result. However, in the latter case, it isappropriate to provide an additional excess of alkali metal amide whichis sufficient to neutralise the residual moisture found in the medium.

According to the invention, the alkali metal amide can be used in anactivated form. It is known that alkali metal amides form, with a verylarge number of hydroxyl derivatives, very reactive bases which havebeen referred to as complex bases. French Pat. Nos. 2,354,834 and2,410,005, granted to Societe Nationale des Poudres et Explosifs,provide a very complete illustration of the main complex bases which areknown and which can be used industrially. According to the invention,the complex base is formed in a known manner and thedihydrocarbylphosphine oxide or sulfide is added to this complex base,after which the second step is carried out as described above. Ascomplex bases which are particularly preferred within the scope of theinvention, there may be mentioned those prepared from sodium amide and atertiary, secondary or primary aliphatic alcohol or polyoxyethyleneglycol monoethers.

It is also known that alkali metal amides form, with the thiocyanates,the cyanates, the nitrites and the cyanides of the main alkali metals,very reactive bases which have been referred to as saline bases. FrenchPat. No. 2,430,428, granted to Societe Nationale des Poudres etExplosifs, provides a very complete illustration of the method ofpreparation of such saline bases. According to the invention, the salinebase is formed in a known manner and the secondary phosphine oxide orsulphide is added to this saline base, after which the second step iscarried out as described above. Particularly preferred saline baseswhich may be mentioned are those prepared from sodium amide andpotassium thiocyanate or, to a lesser extent, potassium nitrite.

According to the invention, the alkali metal amide can also be activatedin the form of a molecular association with an organo-alkali metalcompound of the type described as claimed in a patent application filedin France on the same day as the present Application and entitled "Newassociations of bases resulting from the association of an alkyl-lithiumcompound or aryl-lithium compound with an alkali metal amide or hydride,polymerisation process in which they are used, and product obtained".

These molecular associations can all be used within the scope of thepresent invention. However, those which are more particularly preferredare the ones involving an additional cation effect, which consists inmixing an alkyl-alkali metal compound with an amide of another alkalimetal. Thus, sodium amide being the preferred amide, it isadvantageously associated with an alkyl-lithium compound such asn-butyl-lithium. According to the invention, the molecular associationalkali metal amide/organo-alkali metal compound is formed as describedin the abovementioned Application and the alkali metal (thio)phosphiniteis added to the said association, or vice versa, after which the secondstep is carried out as described above.

The yields of the process according to the invention are generally veryhigh and are fairly dependent on various choices, namely the nature ofthe amide used, the reaction temperature, the solvent used, the natureof the hydrocarbon groups carried by the secondary phosphine oxide orsulfide, and the nature of the organic halogen derivative. Furthermore,if the organic halogen derivative is a polymer, it is not alwaysadvantageous to obtain a very high degree of substitution.

The invention also relates, by way of new industrial products, topolymers carrying groups R₁ R₂ PZ-- (in which Z=S or O) and derived fromhalogen-containing polymers in which the halogens are not highlyactivated as regards their condensation with an alkali metal(thio)phosphinite. It had been impossible to obtain these polymershitherto by the known processes, and they are derived respectively fromp-halogenopolystyrenes and from polystyrenes which are optionallypartially crosslinked and which carry groups of the type --CH₂ --_(p) X,the said polymers being of the general formulae (I) and (II): ##STR5##in which x, y, z and t are numbers such that x+y+z+t=1, 0<x<0.9,0<y<0.5, 0.03<z<1.0 and 0<t/z<0.4, Z being an oxygen or sulphur atom, Xbeing a chlorine or bromine atom and R₁ and R₂ being linear or branchedC₁ to C₁₈ alkyl groups, preferably C₁ to C₁₂ groups and in particularoctyl groups in both cases, for a number-average molecular weight Mnsuch that 20,000<Mn<1,000,000. ##STR6## in which 2<p<12, v, w, x', y'and z' are numbers such that v+w+x'+y'+z'=1, v/y'+z'+w<0.1, 0<x'<0.7,0<y'<0.4, 0<z'<0.1 and 0.03<w<0.9, X=Cl or Br, Z=O or S, R₁ and R₂ areidentical or different and are a linear or branched C₁ to C₁₈,preferably C₁ to C₁₂, alkyl group or a C₇ to C₁₀ arylalkyl group, and Ais a phenyl nucleus of a polystyrene chain of the same type, the groupsA' being in some cases a group X and in other cases a group --PZR₁,R₂,Z, X, R₁ and R₂ having the above meanings.

The various aspects of the invention and also the advance which canthereby be achieved will be understood more clearly with the aid of thefollowing non-limiting examples.

EXAMPLES 1 TO 9 Synthesis of tertiary phosphine oxides

In a 250 ml reactor fitted with a stirrer, the complex base NaNH₂/t-BuONa was prepared in a conventional manner by placing 100 millimolsof NaNH₂, 35 millimols of t-butyl alcohol and 30 ml of tetrahydrofuranin the reactor. The heterogeneous mixture was heated for 30 minutes at40° C., whilst stirring, and the said mixture was then kept at the sametemperature for a further 30 minutes, after which a solution of 33millimols of dioctylphosphine oxide (DOPO) in 50 ml of THF was run intothe said mixture. Two hours after the start of the introduction, thereaction is complete and the presence of sodium phosphinite and also thedisappearance of the DOPO are observed by I.R. spectroscopy. Thisreaction time is much shorter than that required by the method usingsodium metal; furthermore, it is unnecessary to heat the reactionmixture at the reflux temperature of the solvent.

The second step of the process was then carried out by reacting variousorganic halogen compounds with portions of the solution of alkali metalphosphinite obtained in the first step. The molar proportion alkalimetal phosphinite/functional groups in the halogen derivative was 1 forExamples 1 to 9 respectively.

The results obtained are collated in the following table:

    __________________________________________________________________________    Ex-                                                                           ample                                                                             Halogen    Product obtained                                               No. derivative (and yield in %)                                                                              Observations                                   __________________________________________________________________________         ##STR7##                                                                                 ##STR8##       Melting point = 41-42° C. (literatur                                   e: 42-43° C.) Analysis by .sup.13 C                                    NMR.                                           2   n-C.sub.8 H.sub.17 Cl                                                                    (C.sub.8 H.sub.17).sub.3 PO                                                                   Melting point = 51° C.                                 (>60)  (a)      (literature: 51-51.5° C.)                                              Analysis by .sup.13 C NMR.                     3   Cl(CH.sub.2 CH.sub.2 O).sub.3 Bu                                                          ##STR9##       Melting point = 152° C. (literature:                                    152-152.50° C.) Analysis by mass                                      spec- troscopy.                                4   Br(CH.sub.2).sub.3 Br                                                                     ##STR10##      Melting point = 91° C. (literature:                                    145-15020  C.) (b) Analysis by mass spec-                                     troscopy. Analysis by .sup.13 C NMR.                                          Elementary analysis:                                                              C  H  O  P                                                                Found                                                                             70.93                                                                            12.14                                                                            5.07                                                                             10.47                                                            Theory                                                                            71.43                                                                            12.59                                                                            5.44                                                                             10.54                             5   Br(CH.sub.2).sub.4 Br                                                                     ##STR11##      (c)                                            6   Br(CH.sub.2).sub.5 Br                                                                     ##STR12##      (c)                                            7   Br(CH.sub.2).sub.6 Br                                                                     ##STR13##      (c)                                            8                                                                                  ##STR14##                                                                                ##STR15##      Melting point = 55° C. Confirmation                                    by .sup.13 C NMR.                              9                                                                                  ##STR16##                                                                                ##STR17##      (d)                                            __________________________________________________________________________     (a) of nonrecrystallised product.                                             (b) the literature value is questioned because of the consistency of the      spectra with the spectral and elementary analyses.                            (c) structure confirmed both by mass spectroscopy and by .sup.13 C NMR.       (d) this gave 25% of the α-naphthyl derivative and 75% of the           β-naphthyl derivative, which were separated by chromatography on an      alumina column.                                                          

The same procedure was applied to 2-chloropropane, 2-bromopropane,bromobutane, t-butyl chloride and cyclohexyl bromide (Examples 10 to14). No reaction was observed; thus, the process can only be appliedessentially to aromatic halogen derivatives or to aliphatic oraraliphatic derivatives in which at least one halogen atom is carried bya primary carbon. The process was thus applied successfully to BrCH₂ Brand ##STR18## with which, however, expected, totallyphosphorus-substituted products were obtained in a mixture withmono-substituted products, this being explained by the fact that theabovementioned ratio DOPO/X was maintained (Examples 15 and 16).

Furthermore, the process proved to be applicable to secondary phosphinesulphides, in particular Ph₂ PSH, the yields being less good andmixtures being more easily obtained than with the oxides, all otherconditions being equal.

EXAMPLES 17 TO 20 Synthesis of polystyrenes carrying dioctylphosphineoxide groups

The procedure of the preceding examples was repeated usingbromopolystyrenes of the formula: ##STR19## as the halogen derivatives.

Polymer A contained 12.48% by weight of Br, that is to say p=18.5%, andhad an M_(n) of 133,000 (by osmometry).

Polymer B contained 18.8% by weight of Br, that is to say p=30%, and hadan M_(n) of 50,000 (by gel permeation chromatography).

Polymer C, having a molecular weight M_(n) of 184,000 (osmometry),contained 77.43% of C, 6.58% of H and 14.06% by weight of Br, that is tosay p=21.2%.

Polymer D, having a molecular weight M_(n) of 130,000 (osmometry),contained 66.84% of C, 5.42% of H and 27.24% of Br, that is to sayp=48.4%.

These polymers are obtained by brominating polystyrene in CCl₄, in thepresence of anhydrous FeCl₃, the polystyrene itself being obtained byanionic polymerisation of the monomer in THF, at low temperature, thepolymerisation being initiated by naphthalene-sodium.

A solution of alkali metal phosphonite obtained in accordance with thesame procedure as in Examples 1 to 9 was reacted with solutions ofpolymers A to D in THF: the reaction time allowed and the ratioequivalents of DOPO/equivalents of Br have been indicated for eachexperiment.

Bromopolystyrenes, grafted by dioctylphosphine oxide groups, wereobtained in solution in THF. The polymers were recovered byprecipitation in methanol, which eliminated the excess DOPO present.

These polymers, which are soluble in THF, toluene and chloroform, havethe formula: ##STR20##

The characteristics of the polymers obtained are collated in thefollowing table:

    __________________________________________________________________________    Ex- Molar Dura-                                                                             Mn                                                              ample                                                                             ratio tion                                                                              (osmo-                                                          No. DOPO/Br                                                                             (hours)                                                                           metry)                                                                            % C                                                                              % H                                                                              % O                                                                              % P                                                                              % Br                                                                              % y                                                                              % z                                      __________________________________________________________________________    17  14    4   187,000                                                                           -- -- -- 3.25                                                                             2.52                                                                              4.5                                                                              15.8                                     18  6     4   --  -- -- -- 4.54                                                                             1.50                                                                              3.3                                                                              26.0                                     19  6     4   265,000                                                                           83.99                                                                            8.94                                                                             2.25                                                                             3.47                                                                             1.56                                                                              3.0                                                                              17.1                                     20  1.2   4   140,000                                                                           69.09                                                                            6.04  0.85                                                                             23.13                                                                             43.1                                                                             4.1                                      __________________________________________________________________________

Examples 17 to 20 were carried out using polymers A, B, C and Drespectively. It was possible to show by NMR that a small proportion(less than 30% of the total) of the dioctylphosphine oxide groups wereattached in the meta-position of the phenyl groups.

It is seen that an increase in the degree of substitution of the Br bythe phosphorus groups is favoured by an increase in the excess ofsecondary phosphine oxide. This degree can easily be varied from 10 to90% according to the preceding examples.

EXAMPLES 21 AND 22 Synthesis of crosslinked polymers carrying DEPO andDOPO groups

The procedure of Examples 17 to 20 (but carried out at 50° C.) wassupplied to a macroporous bromopolystyrene marketed by ALDRICH under thename Brominated macroporous Polystyrene. This resin, crosslinked with 3%of divinylbenzene, contains from 3 to 4.5 milliequivalents of Br pergram.

10 g of this resin were swollen in 10 ml of THF for 24 hours before theprocess according to the invention was applied.

A ratio secondary phosphine oxide/halide of 6 was used, based on 4.5milliequivalents of Br per g of resin.

Diethylphosphine oxide (DEPO) and dioctylphosphine oxide (DOPO) wereused in Experiments 21 and 22 respectively. The reaction times are 4hours.

This gave crosslinked polystyrenes carrying residual p-bromophenylgroups and carrying dialkylphosphine oxide groups in the para-positionof phenyl groups. The chemical characteristics of these polymers areshown in the following table:

    __________________________________________________________________________                            Milli-                                                Ex-                     equivalents                                                                         Degree of                                       ample       Br %  P %   of P per g                                                                          substitu-                                       No. Phosphorus unit                                                                       by weight                                                                           by weight                                                                           of resin                                                                            tion                                            __________________________________________________________________________    21                                                                                 ##STR21##                                                                            27.93 1.78  0.57  6.0%                                            22                                                                                 ##STR22##                                                                            23.86 1.65  0.53  6.5%                                            __________________________________________________________________________

Although low, the degrees of substitution obtained are nonethelessremarkable because it had hitherto been extremely difficult to initiatesubstitution using conventional methods, in the case of polymers arehighly crosslinked as those used in the two Experiments 21 and 22.

EXAMPLE 23

4 g of sodium amide and 50 ml of THF were placed in a 250 ml reactor.When the medium obtained had been heated to 40° C., 9 g of DOPO were runinto the stirred reactor in the course of 30 minutes.

With the temperature kept at 40° C., 16.5 millimols of1,4-dibromobutane, that is to say a ratio equivalents ofDOPO/equivalents of Br of 1, were run into the resulting mixture in thecourse of 30 minutes. The reaction was left to reach completion for halfan hour at 40° C. and the reaction mixture was precipitated in water.The organic phase was extracted into 100 ml of chloroform and, afterevaporation, 9.3 g of crude product were collected (yield: 94%). Theproduct was recrystallised from hexane and 6.8 g of a product having amelting point of 95° C. were collected (yield: 69%). The product wasidentified by its I.R. and NMR spectra as corresponding to the formula(Oct)₂ PO(CH₂)₄ PO(Oct)₂.

EXAMPLES 24 AND 25

The preceding example shows that, in THF, sodium amide by itself is asreactive towards the secondary phosphine oxide as the amide activated inthe form of a complex base (compare Example 5).

In a solvent of low polarity, which is substantially less polar thanTHF, a comparative kinetic study of the reaction of DOPO with octylchloride, on the one hand in the presence of amide by itself and on theother hand in the presence of amide activated in the form of a complexbase, was carried out.

The initial amounts are those of Example 1 (33 millimols of sodium amidein both cases and 33 millimols of diethylene glycol monoethyl ether) andthe solvent was toluene.

The octyl chloride was present in a 15 mol % excess relative to theDOPO. The reaction was followed by gas phase chromatography. The resultsobtained are collated in the following table:

    __________________________________________________________________________    Ex-               Degree of conversion (in %) after                           ample             0.5                                                                              1.0                                                                              1.5 2.0 2.5                                           No. Reactant      hour                                                                             hour                                                                             hours                                                                             hours                                                                             hours                                         __________________________________________________________________________    24  NaNH.sub.2 by itself                                                                        6  11 15  20  28                                            25  NaNH.sub.2 /Et(O CH.sub.2 CH.sub.2).sub.2 ONa                                               9  40 59  78  82                                            __________________________________________________________________________

It is seen that the use of activated amide makes it possible toaccelerate the reaction when it is carried out in a solvent of lowpolarity.

EXAMPLES 26 TO 33

Sodium amide activated by means of an organoalkali metal compound wasused here. To do this, the association alkali metal amide/organo-alkalimetal compound was first prepared in 50 ml of solvent (THF or toluene,see table), at ordinary temperature, by introducing 25 millimols ofsodium amide and 23 millimols of butyl-lithium (Examples 26 to 31), 25millimols of methyllithium (Example 32) or 25 millimols ofphenyl-lithium (Example 33) into a 250 ml reactor. 20 millimols ofsecondary phosphine oxide (diphenylphosphine oxide in Examples 26 to 31and dioctylphosphine oxide in Examples 32 and 33) were then immediatelyrun into the resulting mixture, in the course of ten minutes and whilststirring. When the addition had ended, the mixture was left for afurther 2 hours at 20° C., whilst stirring. The organic halogenderivative indicated in the table (10 millimols) was added to theresulting reaction mixture in the course of 2 hours, whilst stirring andstill at 20° C. The results obtained are reported in the followingtable:

    __________________________________________________________________________    Ex- Halogen    Sol-                                                                              Product                                                    ample                                                                             derivative vent                                                                              obtained       Characterisation                            __________________________________________________________________________    26  BrCH.sub.2Br                                                                             THF Ph.sub.2 POCH.sub.2 POPh.sub.2                                                               by MS (a)                                   27  Br(CH.sub.2).sub.3 Br                                                                    THF Ph.sub.2 PO(CH.sub.2).sub.3 POPh.sub.2                                                       by MS (a)                                   28  Br(CH.sub.2).sub.4 Br                                                                    THF Ph.sub.2 PO(CH.sub.2).sub.4 POPh.sub.2                                                       by MS (a)                                   29  Br(CH.sub.2).sub.5 Br                                                                    THF Ph.sub.2 PO(CH.sub.2).sub.5 POPh.sub.2                                                       by NMR (b)                                  30  Br(CH.sub.2).sub.6 Br                                                                    THF Ph.sub.2 PO(CH.sub.2).sub.6 POP.sub.2                                                        by NMR (b)                                  31                                                                                 ##STR23## PhCH.sub.3                                                                         ##STR24##     by NMR (b) and MS (a)                       32                                                                                 ##STR25## PhCH.sub.3                                                                         ##STR26##     by NMR (b) and MS (a)                       33  Br(CH.sub.2).sub.6 Br                                                                    PhCH.sub.3                                                                        Oct.sub.2 PO(CH.sub.2).sub.6 POOct.sub.2                                                     by NMR (b) and MS (a)                       __________________________________________________________________________     (a) Analysis by mass spectroscopy, verification that the expected peaks       are obtained.                                                                 (b) Analysis by .sup.13 C nuclear magnetic resonance.                    

EXAMPLE 34

4 g (100 millimols) of sodium amide in 30 ml of toluene were placed in a250 ml reactor, this mixture was heated for 2 hours at 40° C., 9 g (33millimols) of DOPO in 60 ml of toluene were then added and the mixturewas heated for 2 hours at 40° C., whilst stirring.

The I.R. spectrum of the resulting mixture shows that sodiumdioctylphosphinite had been formed.

33 Millimols of Br(CH₂)₄ Br are added to the reaction mixture and thereaction is left to proceed for 1 hour at 40° C., whilst stirring. Thedegree of conversion obtained after this time is 20%.

EXAMPLES 35 AND 36

100 Millimols of sodium amide and 50 millimols of sodium thiocyanate in30 ml of toluene were placed in a 250 ml reactor. The mixture wasstirred for 2 hours at 40° C., after which a solution of 35 millimols ofDOPO in 60 ml of toluene was added to the resulting medium. The reactionmixture was stirred for 2 hours at 40° C. A composition containingsodium dioctylphosphinite and not showing a P-H band in the infra-redspectrum (no residual phosphine oxide) was then obtained.

Br(CH₂)₄ Br (33 millimol-equivalents of bromine) was then added to thiscomposition and the reaction was left to proceed for 1 hour at 40° C.

The reaction medium obtained was precipitated in water, the organicphase was extracted with chloroform and the chloroform extract was thendried with MgSO₄. After evaporation of the solvent and thenrecrystallisation from hexane, 6.3 g of 1,4-di-(dioctylphosphineoxide)-butane were obtained, that is to say a yield of 65% of purifiedproduct (melting point: 99°-99.5° C.).

A comparable result was obtained on replacing KSCN by NaNO₂ (the yieldis slightly lower).

We claim:
 1. Process for the synthesis of a tertiary phosphine oxide orsulfide of formula R₁ R₂ R₃ PZ, in which Z=S or O,R₁ and R₂ areidentical or different and are a linear or branched C₁ to C₁₈ alkyl, C₇to C₁₀ arylalkyl, phenyl, C₇ to C₁₂ aryl, C₇ to C₁₀ alkaryl, or R₁ andR₂, taken together, form a C₄ to C₉ polymethylene chain or a C₄ to C₉hydrocarbon chain containing at least one ethylenic unsaturation; R₃ isan organic halogen or polyhalogen compound containing at least onehalogen atom in the form of a halogenoaryl group or halogenomethylgroup; which consists of:(a) reacting a dihydrocarbylphosphine oxide orsulfide R₁ R₂ PZH, in which R₁, R₂ and Z are as defined hereinabove with1.1-6 molar equivalents of an alkali metal amide of formula MNH₂ inwhich M is an alkali metal whereby an alkali metaldihydrocarbylphosphinite or thiophosphinite of formula R₁ R₂ PZM inwhich R₁ R₂ Z and M are as defined hereinabove is obtained, and then(b)reacting said compound of formula R₁ R₂ PZM from step (a) with anorganic halide of formula R₃ X in which R₃ is as defined hereinabove andX is Cl, Br or I and isolating said tertiary phosphine oxide or sulfidefrom the reaction mixture.
 2. Process according to claim 1, wherein thealkali metal amide is activated in the form of molecular associationsbased on an alkali metal alcoholate, based on a salt which is a memberselected from the group consisting of the thiocyanates, the cyanates,the nitrites and the cyanides of sodium, lithium or potassium, or basedon an organo-alkali metal compound.
 3. Process according to claim 1,wherein in the organic halide of the formula R₃ X R₃ is an aromaticgroup which is unsubstituted of substituted by X atoms and containingfrom 6 to 14 carbon atoms, X being Cl, Br or I, or a group CH₂ R₄, inwhich R₄ is a linear or branched primary alkyl containing from 1 to 18carbon atoms, a primary aralkyl containing from 7 to 14 carbon atoms, analkaryl containing from 7 to 14 carbon atoms or a primary alkylenecontaining from 3 to 18 carbon atoms, one unsaturation not beingdirectly bonded to X, or a group --CH₂ X, in which X has one of theabove meanings, or a group --CH₂ R₅ X, in which X has one of the abovemeanings and in which R₅ is a hydrocarbon chain containing from 1 to 18carbon atoms, or a group ##STR27## in which X has one of the abovemeanings, or a crosslinked macromolecular group or a macromoleculargroup with a molecular weight of between 500 and 1,000,000, containingat least one other group X carried by an aromatic nucleus or a primarycarbon of an aliphatic chain.
 4. Process according to claim 1, whereinbetween 1 and 20 mols, of alkali metal amide are used per mol ofdihydrocarbylphosphine oxide or sulphide.
 5. Process according to claim1, wherein between 0.1 and 20 mols, of dihydrocarbylphosphine oxide orsulphide are used per mol of halogen.
 6. Process according to claim 1,wherein the reaction is carried out in the presence of an inert solventand at between -20° and +70° C., for the first step, and at between -20°and +100° C., for the second step.
 7. Process according to claim 2,wherein the molecular association based on the alkali metal alcoholateis a complex base prepared from a tertiary, secondary or primaryaliphatic alcohol or polyoxyethylene glycol monoethers.
 8. Processaccording to claim 2, wherein the molecular association is based onpotassium thiocyanate or nitrite and based on sodium amide.
 9. Processaccording to claim 2, wherein the molecular association is obtained bymixing an alkyl-alkali metal compound with an amide of another alkalimetal.
 10. Process according to claim 3, wherein the organic halide is apolymer which is a member selected from the group consisting ofchloromethylated polystyrene, polystyrene substituted bybromopolymethylene groups, poly-(p-bromostyrene), poly-(p-chlorostyrene)and bromopolybutadiene or is a copolymer containing styrene and (1)chloromethylated styrene, (2) styrene substituted by bromopolymethylenegroups, (3) p-bromostyrene, (4) p-chlorostyrene or (5) bromobutadiene.